This invention relates to integrated circuit header assemblies and, more particularly, to an assembly comprising an integrated circuit (IC) die mounted to a header assembly and method for making the same. The integrated circuit header assembly used in electron bombarded charged coupled devices (EBCCDs) provides improved control of the spacing between the die and the cathode and accommodates combinations of materials having different coefficients of thermal expansion.
Integrated circuit devices are typically fabricated from semiconductor or silicon dies that are mounted in modules that can include supporting carriers or substrates and headers. In applications where the IC die is fragile or subject to further processing, the IC die can be mounted to a substrate or carrier to provide further support or facilitate further processing. Typically, the IC die carrier (or substrate) assemblies are subsequently mounted to a header which includes pins or other leads which allow the device to be electrically and mechanically connected to the system in which is used. The header can facilitate mounting the IC module to a circuit board, a mating socket or module housing or enclosure. Typically, fine gold wires are bonded to conductive pads on the die or the carrier and the header to establish electrical connections between the pins or leads of the header and the integrated circuit on the die.
In EBCCDs, the spacing between the IC die and the cathode determines the acceleration voltage required. In prior art devices, the header includes an integral pedestal that fixed the amount of reentrance (the distance between the IC die and the cathode) at the time of the header was fabricated. This required a different header for each different type of EBCCD tube. In addition, because the header is constructed from materials which match the thermal expansion coefficient of the side walls of EBCCD tube, it is not a good thermal expansion match for the silicon IC die. The stresses caused by the thermal expansion mismatch can cause the EBCCD die to warp or crack.
Accordingly, it is an object of this invention to provide an improved integrated circuit device.
It is another object of the invention to provide an improved header subassembly device for supporting an IC die.
It is yet another object of the invention to provide an improved integrated circuit device that is suitable for processing and use in higher temperature environments.
It is a further object of the invention to provide an improved circuit device comprising an integrated circuit die mounted to a header wherein thermal coefficients of expansion of the components are selected to reduce the stress associated with thermal expansion of different materials having different expansion coefficients.
It is a further object of the invention to provide an improved method of mounting an integrated circuit device to a header.
It is a further object of the invention to provide an improved method of mounting a electron bombarded charged coupled device to a header.